Tuesday September 19, 2006
Orang utan head count
A survey to find out the number of orang utans in Sarawak is under way, writes HILARY CHIEW.
MENTION Batang Ai, Sarawak, and chances are people will visualise a certain five-star resort and hydroelectric dam. Few would know that the forested area is the last stronghold of the endangered orang utan in Sarawak.
Last surveyed in 1992 by the Wildlife Conservation Society (WCS) and the then Sarawak Forestry Department, the Batang Ai park is estimated to host between 62 and 824 orang utans.
Together with the Bentuang-Karimun Nature Reserve across the border in Kalimantan, Indonesia, the forest complex in the south-west corner of Sarawak forms the largest protected area where the orang utan is found, and is recognised as a key area for survival of the species.
The area is also earmarked as the country’s first terrestrial trans-frontier park, which protects biodiversity that utilises the forest beyond political boundaries. As forests outside the protected areas are found to host a significant number of orang utans, there are plans to enlarge the Batang Ai park and create the new Ulu Sebuyau National Park.
Over the past two years, WCS researchers have surveyed the site to re-estimate the orang utan population and assess long-term threats. The data would be used to develop a conservation strategy for orang utans in Sarawak.
WCS Malaysia Programme director Dr Melvin Gumal says the habitat, largely unspoilt as it was never logged, has vital forest cover to sustain orang utans. He says shifting cultivation was done there over 50 years ago and the forest has regenerated since. He declines to disclose the survey results but says more work is needed to confirm that the population has not plummeted.
The research team headed by June Rubis conducted nest counts from early 2004 to January 2005 on 11 sites in Batang Ai. In March 2005, the survey was extended to Lanjak-Entimau where out of 10 sites, seven have been completed.
Nest count is a common field method to estimate orang utan numbers as the arboreal ape generally builds a new nest to sleep in every night. The method involves dividing the survey area into transects. Rubis and her field assistants walk the 2km transect twice daily, recording the occurrence, location and decay stage of nests.
Then, using a computer software programme called Distance 5, the team calculates the population density based on the proportion of nest-builders in the population, the rate at which nests are produced and the nest decay rate.
Some transects were surveyed for new nests twice to improve the accuracy of population estimates. When the first phase is completed, the researchers would have thoroughly combed through both protected areas.
Besides WCS, the project is funded by the United States Fish and Wildlife Services, Orang Utan Foundation International-UK and local tour operator Borneo Adventure.
In the pipeline is a conservation education component to inform target groups – local communities, the relevant authorities, oil palm growers and travel companies – on the importance of conserving orang utans and their habitat.
Life of adventure